Rotary window for gas inspection



F. C LEONARD ROTARY WINDOW FOR GAS INSPECTION Mam-d124, 1959 3 Sheets-Sheet 1 Filed June 22, 1956 March 24, 1959 F. c. LEONARD 2,373,716

ROTARY WINDOW FOR GAS INSPECTION Filed June 22, 1956 3 Sheets-Sheet 2 3 Sheets-Sheet 3 Filed June 22, 1956 United States 2,878,716 ROTARY WiNDOW FOR GAS INSPECTION Frederic Charles Leonard, Biackheath, London,

assignor to Elliott Brothers (London) England, a company of Great Britain England, Limited, London,

This invention relates to improvements in windows and within the passage to be measured. may he mentioned the arrangement n which WlIidOWS are adapted to be arranged in the wall or other radiation to enable the density of measured.

such as heat or light, across the flue, to

a heat or light-sensitive device externally of the flue. These windows disadvantage that the inside surface thereof, fouled in use due to the deposition thereon of solid particles from the flue gases so that the degree of transparency of the Windows varies and affects the reliability of the measurements made. Such windows require constant attention and cleaning.

It is an object of the present invention to provide an improved window which shall not be subject to the disadvantage referred to.

According to the present invention, a window adapted or adjacent to an aperture in a wall defining a passage, e.g. a chimney or fine, comprises a about an axis and substantially transparent liquid over at least a part of that surface exposed to the interior of the passage.

In a preferred arrangement according to the present invention, a window adapted to be arranged in or adjacent to an aperture in a Wall defining a passage, e.g. a of transparent maaxis normal to the direction of length of the passage and disposed relative of the chimney or least a part of the inner surface of the sheet overlies the aperture for all angular displacements of the sheet relative to said axis,

the sheet adjacent to said axis, the sheet at a relatively high speed about said axis to cause the liquid to move outwards from the axis over the inner surface of the sheet in the form of a thin film under the effect of the centrifugal force produced by rotation of the sheet.

Conveniently means is provided around the periphery 2,878,716 Patented Mar. 24, 1959 2 of the sheet to collect the liquid as it moves outwards beyond this periphery.

One embodiment of the invention as applied toappathe smoke content The transmitter 1 and the H.P. motor 5 connected by means of a shaft 6 to a spindle 16 of the chamber. The wall 16 is carried on a defined by an inner annular surface of the disc and a cup-shaped member. The cup-shaped members are indicated at 28 and 29 respectively and are each formed centrally of the base with an aperture through which the spindle 7 extends as a relatively close fit, the

disposed annular groove in the fluid-tight seal where the latter passes through the cup-shaped members 28 and 29. Each cup-shaped member .is formed in its base with an annular groove 31 within which is received an annular sealing ring 32 and there is disposed in each cup-shaped memher a disc 33 which bears against the associated sealing ring 32 and which carries a the disc 25 to space this inner end of the lip of the associated cup-shaped member a short distance of the order of 0.002 to of the glass disc 25. On end of the lip of each cup-shaped member is formed with a knife-edge '35; Intermediate its length the spindle 7 is aavsme formed with an annular enlargement 36 having an an nular groove 37 in one of its faces within which is received an elastic sealing ring 38. The cup-shaped members 28 and 29 with the disc 25 clamped between the vanes 33a in the respective chambers 26 and 27 form an assembly which is clamped on to the spindle 7 and urged against the annular enlargement 36 and the elastic sealing ring 38 by means of a nut 39 which threadedly engages the end of the spindle 7 remote from that to which the shaft 6 is attached. The elastic ring 38 and to some extent the sealing rings 32 provide a cushioning effect which prevents the glass disc 25 being clamped too tightly between the vanes 33a as the nut 39 is screwed on to the spindle 7. A throw-ring 40 is attached to the spindle 7 adjacent its other end.

Surrounding the periphery of the glass disc 25 is a trough 41 having two deflecting surfaces 42 arranged to deflect away from the disc 25 any liquid thrown off therefrom in a radially outward direction, the deflected liquid being collected in channels 43. The trough 41 is formed at its lower end with an opening 43a disposed above the reservoir 19. A priming pump 44 is provided for pumping liquid from the reservoir 19 to the chamber 14 and the chambers 26 and 27. The motor is mounted on the reservoir 19. In the case of the transmitter 1 a light source and lens system indicated generally at 45 are mounted on the housing of the motor 5 and are arranged to project a beam of light through a part of the disc 25, through an opening 46 in the casing 4 and across the fine 3 through openings 47 formed in the wall thereof. In the .case of the receiver 2 a lens system and photo-cell indicated generally at 48 are carried on the housing of the motor 5 and are disposed to receive through an aperture 49 in the associated housing 4 and through the associated glass disc 25 the beam of light transmitted across the flue 3 from the transmitter 1. It is preferred as shown to provide means for modulating the intensity of the light beam such as the chopper disc 50 which is carried on the spindle 7 of the transmitter 1 and is arranged periodically to obscure the light beam so that the signal received by the receiver will be pulsed and the pulsed electrical output from the photo-cell thereof will be capable of ready amplification.

In the operation of the apparatus described, water is pumped with the aid of the priming pumps 44 from each reservoir 19 to the associated chamber 14 to fill the associated passage and the associated chambers 26 and 27. The motors 5 are then started to rotate the associated spindle 7 and the glass disc 25 and cup-shaped members 28 and 29 thereon at a suitable speed, e.g. 1420 r.p.m. Each set of vanes 33a expels the water from the associated chamber 26 or 27 radially outwards of the disc through the small annular gap between the knifeedges 35 and the adjacent face of the disc 25 to spread a film of water over both surfaces of moves outwards under centrifugal force due to rotation of the disc 25 and which has a thickness determined by the width of the annular gap referred to. As the water reaches the periphery of the disc 25 it is thrown off therefrom into the trough 41 against the deflecting surfaces 42 which deflect it into the channels 43. The water runs down the channels 43 to the bottom of the trough 41 and out through the reservoir 19, the rotation of the vanes 33a acting as a pump drawing up water from the reservoir 19 so that there is always a continuous film of water flowing over both surfaces of the disc 25. The throw ring 40 in both the transmitter 1 and the receiver 2 prevents any water working back along the spindle 7 to the motor 5.

The apparatus described is preferably arranged to project a beam of light through a part of the flue 3 in which the pressure of the gases is sub-atmospheric so that there will be a tendency for air to leak into the flue from the atmosphere through the apertures 47 rather than for the gases in the flue to leak out through these apertures.

the disc 25 which the opening 43a back to.

If desired the pressure of the air within the housings 4 may be artificially maintained at a pressure greater than that of the gases of the flue 3. However, some proportion of these gases will leak out through the apertures 47 and the solid particle content of these gases is substantially prevented from reaching the rest of the apparatus by the glass discs 25 upon which these particles tend to settle. The continuously flowing film of water on the faces of the glass discs 25 carries these solid particles away to the reservoir 19 and keeps the glass disc 25 clean and transparent so that the modulation of the pulses of light transmitted across the flue is entirely due to the amount of light absorbed by the gases in the fine 3 and the output from the photo-cell in the receiver 2 is a true function of the smoke content of these gases. A suitable filter may be provided to remove the solid particles washed off the disc before the water from the reservoirs 19 is fed again to the discsand this recirculation of the water is advantageous where it is not con venient to supply continuously large volumes of water to the apparatus although it will be appreciated that it is necessary to supply make-up water to the reservoir 19 to replace water lost through evaporation. Thus the volume of water used by the apparatus may be maintained at a minimum.

It is an important feature of the apparatus described that the disc 25 together with the cup-shaped members 28 and 29 and the vanes 33a are all clamped on the spindle 7 so that there are no relatively moving parts.

It will be appreciated that the liquid used need not necessarily be water but may be any other suitable trans parent liquid, although water is to be preferred as it is readily available. Alternatively the liquid may be an aqueous solution, e.g. a solution of a detergent in water, which will prevent the faces of the discs 25 tending to become greasy in use.

It will be further appreciated that the disc 25 although described as having plane parallel faces may have convex or concave faces, the only requirement being that the surfaces of the annular portion of the disc 25 through which the light beam passes should be smooth.

The vanes 33a disposed in each cup-shaped housing 28 and 29 may be cast integrally therewith in which case the disc 33, sealing ring 32 and annular groove 31 are not required.

It will be appreciated that the essential feature of the invention is to provide a substantially even thin film of a transparent liquid over that part of the disc traversing the light beam. This may be achieved by spraying the liquid on to the surface of the disc from a number of ets or nozzles extending radially or diametrically of the disc and disposed opposite this surface and providing a radially extending knife-edge spaced at small distance from this surface and disposed between such nozzles and the light beam considered in the direction of rotation of the disc so that after the liquid is sprayed on to the sur face of the disc it is spread by the knife edge into a thin substantially even film before that part of the surface of the disc over which it flows is illuminated by the light T beam.

What I claim is:

1. In apparatus for determining the condition of a gas flowing through a passage having an apertured wall through the aperture in which radiation may pass in its path between radiation-transmitting means and radiationreceiving means disposed externally of said passage, a window comprising a transparent disc located externally of said passage with one face thereof closely adjacent to said aperture and mounted for rotation about an axis substantially parallel to the path of the radiation passing through said aperture so that a peripheral operative zone of the disc may be traversed across said path, means for continuously supplying a transparent liquid to a central zone of said disc at least on said face thereof and means for rotating said disc to cause said liquid to travel'outwards under the action of centrifugal force over said peripheral operative zone in the form of a thin film.

2. Apparatus as claimed '21 claim 1, thickness-restricting means of to the operative zone.

3. Apparatus as in claim 2, wherein said film thicknessrestricting means comprises a cup-shaped member dis means for supplying connected with said chamber.

4. Apparatus as claimed in claim 3, including liquidimpelling vanes disposed Within said chamber and arranged to urge the liquid delivered into said chamber towards the outlet therefrom.

5. Apparatus as claimed mounted liquid being a connection to said reservoir.

8. Apparatus as claimed in claim trough comprises deflecting surfaces disposed between said channels radially opposite the periphery 9. In apparatus for flowing through through the aperture in path between radiation-transmitting and radiation-re- 6 to said operative zone, and means for rotating said disc to cause said liquid to travel outwards under the action over said peripheral zone in the form member being said disc, said cup-shaped member defining with said face of said disc a References Cited in the file of this patent UNITED STATES PATENTS Simon et a1. Dec. 15, 1933 Grant Nov. 26, 1949 

